Shotline trap



Al" 15L- 4 FIG. 2A,

In ML INVENTOR. ROBERT L DA V/S ATTORN YS.

United States Patent Ofiice SHOTLINE TRAP Robert L. Davis, Plainview, Company, Philadelphia, Jersey Tex., assignor to Sun Oil Pa, a corporation of New This invention relates to a shotline trap and more particularly to a trap device for use when explosives are detonated within holes bored into the earths surface to trap or prevent the shot lines from being blown out of the hole by the force of the explosion.

in seismic prospecting explosive charges are fired in bore holes to set up seismic waves which are detected at remote points afterrefiection. or refraction. These operations are referred to as shooting and the electrical lines used for firing the explosive are referred to as shotlines.

Shooting operations are attended with the problem of preventing the shotlines involved from being blown up out of the hole by the force of the explosion resulting in possible danger and damage. Particular hazard exists when these operations are carried out in the presence of overland high tension electric power lines so that, if cables blown out of a well descend upon such power lines, great damage will result.

It is an object of this invention, therefore, to provide a shotline trap which may be inserted into a bore hole and locked therein to prevent the shotline from being blown out of the hole by the force of the explosion and which will, at the same time, permitthe passage of gas and vapor resulting from the blast.

It is a further object of the invention to provide apparatus which may be locked into a bore hole to prevent a shotline from being blown out of the hole by the force of the explosion therein and which may be readily removed from the bore hole after the explosion has occurred.

These and other objects of the invention will become apparent from the following description read in conjunction with the accompanying drawings, in which:

Figures 1A and 1B are sectional views of a bore hole within the earth showing apparatus according to the present invention, partially cut away, engaging the wall thereof; and

Figures 2A and 2B are sectional views of a bore hole showing apparatus in accordance with the present invention disengaged from the wall thereof preparatory to the removal of the apparatus from the bore hole.

The figures show a section of the earth containing a bore hole 2 extending downwardly from the surface thereof. Inserted into the bore hole is the rod member 4. Afiixed to the rod member 4 are the blocks 6 containing bores within which is rotatably mounted the rod member 8. The upper ends of the rod members 4 and 8 are formed with loops shown generally at 10 and 12, respectively, which are provided to permit an operator to grip and support the rod member 4 and to rotate the rod member 8 for purposes as will be hereinafter described.

The lower end of the rod member 4 is threaded into the block 14 and locked into position by means of the lock nut 16. Afiixed to the block member 14, and welded together at their lower ends, are the four tines or spear members 17, 18, 19 and 20, the members 18 and 20 being partially cut away in Figure 1. The upper ends of 2,720,834 Patented Oct. 18, 1955 2 the spear members are flared outwardly and their upper portions 21 are adapted to engage the earth forming the wall of the bore hole, as shown in Figure 1A. The spear members are made of spring steel or the like and normally tend to expand outwardly.

The ring member 22 encircles the spear members at approximately the center of their length. The ring 22 is joined by means of spokes 24 to the off-center hub member 26 which contains a threaded internal bore engaging the threaded lower end 28 of the rotatably mounted rod member 8. The rod member 8 rests upon the step member 30 which is attached to the spear member 17.

The collar 32 is rigidly affixed to the rotatable rod 8 and is adapted to bear against the adjacent block member 6. Itwill be apparent that the collar 32 bearing against the adjacent block member 6 will prevent upward motion of the rod 8 relative to the rod 4 and the step 30 will prevent downward motion of the rod 8 relative to the rod. 4. Therefore, as the rod member 8 is rotated the off-center hub 26, which will not rotate due to the contact of the spokes 24 with the rod member 4 or one or more of the spears, will be raised or lowered on the threaded portion 28 depending upon the direction of rotation of the rod member.

Figure 1A shows the apparatus with the hub member 26 and the ring 22 in approximately a lowermost position permitting the upper ends 21 of the spear members to flare outwardly in response to their own spring tension and to engage the earth forming the wall of the bore hole. Figure 2A shows the apparatus with the off-center hub member 26 in approximately an uppermost position whereat the ring member 22 engages the upper portions of the spear members and draws them inwardly holding them clear of the inside wall of the bore hole.

As the spear member 17 moves inwardly and outwardly the step 30 will also move inwardly and outwardly. The step will, however, slide back and forth under the end of the rod 8 and the freedom of rotation of the rod will obviously not be affected by the position of the step.

As shown in Figure 2A, the shotline trap may be arranged to be readily raised or lowered within the bore hole and, when it is desired to set the assembly in position in the bore hole, the rod member 8 is rotated causing the hub 26 and the ring member 22 to move downwardly with respect to the spears, permitting the spears to move outwardly in response to their own spring action and if, as they engage the wall of the bore hole, the assembly is pulled upwardly, it will be apparent that the upper ends 21 of the spear members will pierce the earth and lock the assembly in position as shown in Figure 1A.

When it is desired to remove the trap from the bore hole, the rod member 8 will be rotated in order to carry the hub 26 and the ring 22 upwardly and the apparatus will be forced downwardly in order to pull the upper ends 21 of the spear members out of the holes 34 in the wall of the bore hole. The rod member 8 will be further rotated to carry the ring member 22 to its uppermost position whereat the ends of the spears are held completely clear of the walls of the bore hole and the apparatus may be freely withdrawn therefrom.

When it is desired to set oil? a charge within a bore hole the charge and the shotline involved will be lowered into the bore hole to their proper positions, after which the shotline trap is inserted into the upper end of the hole above the charge and caused to engage the walls of the hole as has been previously described. When the four spear members flare outwardly to engage the walls of the hole, ample space will exist between the individual spears for the passage of necessary lines to the surface of the earth and to permit the passage of the gas and vapors resulting from the blast. However, when the explosive charge is detonated, the shotline which is carried upwardly by the force of the blast will strike against the flaring spear members forming a somewhat tangled mass which will not pass beyond the spear member and the upward thrust will be carried by the spear members into the earth surrounding the bore hole. At the termination of the blast, the portion of the shotline driven upwardly by the blast will generally drop clear of the trap permitting the trap to be readily withdrawn from the bore hole. After the removal of the trap from the bore hole, the shotline may be removed therefrom.

It will be apparent that this invention provides a simple practical means for preventing a shotline from being blown out of a bore hole by the force of a shot blast therein, and yet, provides apparatus which may be readily removed from the hole after the blast, and which may be used repeatedly. It will also be apparent that the apparatus, as disclosed herein, may be variously modified without departing from the invention as set forth in the following claims:

What is claimed is:

1. A shotline trap adapted to be inserted into and removed from a bore hole comprising a plurality of elongated flexible spear members, means fixedly mounting a lower portion of each of said spear members adjacent to each other, the upper portions of said spear members being urged outwardly above said mounting means by their own spring action, substantially rigid means for supporting said mounting means in a bore hole from the surface of the earth, retaining means operatively connected to said spear members between the ends thereof, and rotatable means operable from the surface of the earth for selectively actuating said retaining means to move the upper portions of said spear members inwardly clear of the wall of the bore hole against the urging of their spring action to permit the trap to be raised or lowered therein, or to permit the upper portions of the spear members to expand outwardly into engagement with the wall of the bore hole in response to the urging of their own spring action to secure the trap within the bore hole.

2. A shotline trap adapted to be moved from a bore hole comprising a plurality of elongated flexible spear members, means fixedly mounting a lower portion of each of said spear members adjacent to each other, the upper portions of said spear members being urged outwardly above said mounting means by their own spring action, a rod for supporting said mounting means in a bore hole from the surface of the earth, a second rod extending from the surface of the earth terminating in the region of said spear members and having its lower end threaded, retaining means slidable against outwardly facing surfaces of said spear members between the ends thereof, a member engaging the threads on said second rod and means connecting sa1d member to said retaining means, said member, said retaining means and said connecting means being movable upwardly and downwardly within the bore hole by rotation of said threaded second rod, said retaining means when moved upwardly moving the upper portions of said spear members inwardly clear of the wall of the bore hole against the urging of their own spring action to permit the trap to be raised or lowered therein and when moved downwardly permitting the upper portions of the spear members to move outwardly into engagement with the wall of the bore hole in response to the urging of their own spring action to secure the trap within the bore hole.

inserted into and re- References Cited in the file of this patent UNITED STATES PATENTS 478,024 Rose June 28, 1892 615,321 Straub Dec. 6, 1898 921,144 McGregor May 11, 1909 1,153,450 Schafi Sept. 14, 1915 1,282,479 Smith Oct. 22, 1918 2,450,366 Williams Sept. 28, 1948 2,472,997 Williams June 14, 1949 2,576,412 Ogburn Nov. 27, 1951 FOREIGN PATENTS 84,007 Switzerland Feb. 2, 1920 

